This invention relates to a high pressure fuel injection device for an engine and more particularly to an improved electromagnet assembly and general overall configuration for such a fuel injection device.
One popular form of fuel injection device for engines is the so-called "accumulator type". This type of injection nozzle includes an accumulator chamber that is charged with fuel under pressure and which communicates with a nozzle port. An injection valve is supported within the accumulator chamber and controls the discharge through the nozzle port. An actuating device is associated with the injection valve and is moveable within a control chamber that is also pressurized with fuel. A relief valve is associated with the control chamber and is opened so as to reduce the pressure and cause the pressure in the accumulator chamber to unseat the injection valve and initiate fuel injection.
Normally the relief valve is operated by an electromagnet assembly that is contained within the housing of the fuel injection nozzle. Although this type of injection system is quite effective, the positioning of the electromagnet within the housing can give rise to stray flux paths which will adversely effect the operation of the device and its responsiveness. For example, when the supporting yoke of the electromagnet is disposed adjacent and in close contact with the outer housing, this stray flux path can significantly reduce the responsiveness of the relief valve and, accordingly, the operation of the system.
It is, therefore, a principal object of this invention to provide an improved electromagnet assembly for this type of fuel injection nozzle.
It is a further object of this invention to provide an electromagnet assembly for a fuel injection nozzle wherein stray flux paths are substantially eliminated.
With the type of injection nozzle described, it is, of course, necessary to provide a supply conduit for supplying the pressurized fuel to both the accumulator chamber and the control chamber. In addition, a return line must also be incorporated so as to provide a path for return flow of fuel from the control chamber back to the fuel tank. With conventional types of injection nozzles, these passages or at least one of them have been disposed at an angular relationship to the nozzle housing. As a result, when the nozzle is screwed in place into the engine, the passages may not be appropriately located and, accordingly, shimming or adjustment is required.
It is, therefore, a further object of this invention to provide an improved nozzle assembly for a fuel injection system wherein the fuel supply and return ports are located in such a position that the angular position of the nozzle in the engine will not present a problem.